I want to setup RAID 5 with four drives. Later on I plan on adding one more at least. Will I be able to add a drive easily to an existing RAID 5 system or do all disks need to be added at once?
We do not support adding drives to a RAID volume like this. Sorry
In posts 5 years ago it was mentioned that this was something you were working on. And it's something I've been doing in Linux since the late '90s.
Is this going to be a feature soon?
No it is not. Sorry
I mean, you're not really sorry if you're choosing not to implement industry standard features you've said were in the works for half a decade.
It is not a "standard" as it is implemented different everywhere. (some "solutions" just concatenate the extra storage to the end, which is not even redundant) For us to do it correctly, we would have to relocate all data on the disks. If we were working only with exclusively solid, stable hardware, yes we could, but as we would need to support all manner of hardware, and users are known to use funky hardware configurations, so it is risky.
Plus, we have to support it. Tons of testing is required for that. Its a lot of work and few users require it. We have other features in mind we believe will be more valuable.
Sorry. Maybe someday, but not in the near future.

